In the recent years, many countries has focused on promoting digital television (DTV) services to effectively use available finite frequency bands and to improve quality of audio and video transmission. Antennas for receiving signals transmitted by wireless TV stations serve as intermediate elements between an audio-video device and the wireless TV stations. The antennas convert electric signal to electromagnetic wave and vise versa, and are configured to reduce attenuation loss of electromagnetic wave at a specific frequency band to thereby increase signal-to-noise ratio (SNR) of received signals.
Referring to FIG. 1, a conventional antenna includes two hollowed symmetric triangular structures 11 for transceiving signals having a frequency falling within a bandwidth, for example 470˜700 MHz, for DTV. The conventional antenna provides antenna gain as shown by a dashed line in FIG. 3.